#!/bin/bash
#
#   pacman-cage
#
#   Copyright (c) 2002-2006 by Pablo Nicolas Diaz <pablonicolas.diaz@gmail.com>
#   Copyright (c) 2002-2006 by Andrew Rose <rose.andrew@gmail.com>
#   I used Judds pacman-optimize as a framework.
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
#   USA.
#

myver='2.9.8.3'
dbroot="/var/lib/pacman/"
pacmandb="/var/lib/pacman-X.db"

# filesystem used in pacmandb
filesystem="ext2"
# commandline needed for mkfs.$filesystem and dd
BlockSize="1024"
Options="-F -O dir_index -b $BlockSize -i 1024 -m 0"
# temporal mountpoint 
pacman_tmp_mnt_point=/mnt/tmp-pacman

usage() {
        echo "pacman-cage $myver"
        echo "usage: $0 [pacman_db_root]"
        echo
        echo "pacman-cage creates a loopbacked filesystem in a contigious file."
        echo "This will give better response times when using pacman"
        echo
}

die() {
        echo "pacman-cage: $*" >&2
        exit 1
}

die_r() {
        rm -f /tmp/pacman.lck
        die $*
}

if [ "$1" != "" ]; then
        if [ "$1" = "-h" -o "$1" = "--help" ]; then
                usage
                exit 0
        fi
        dbroot=$1
fi

# test if filesystem support is present
if ! grep $filesystem /proc/filesystems > /dev/null; then
    die "filesystem $filesystem is not supported!" 
fi

# added by wain: make sure kernel support loop device
if ! zcat /proc/config.gz | grep "BLK_DEV_LOOP=\(y\|m\)" >/dev/null; then
       die "please enable loop device support in kernel (BLK_DEV_LOOP=y)"
elif [ -d /dev/loop/ ]; then 
       die "You must insert the loopback module!"
fi

if [ "`id -u`" != 0 ]; then
       die "You must be root to cage the database"
fi

# make sure pacman isn't running
if [ -f /tmp/pacman.lck ]; then
        die "Pacman lockfile was found.  Cannot run while pacman is running."
fi
# make sure pacman.db hasnt already been made
if [ -f $pacmandb ]; then
        die "$pacmandb already exists!."
fi

if [ ! -d $dbroot ]; then
        die "$dbroot does not exist or is not a directory"
fi

# don't let pacman run while we do this
touch /tmp/pacman.lck
 
# step 1: sum the old db
echo "==> md5sum'ing the old database..."
find $dbroot -type f | sort | xargs md5sum >/tmp/pacsums.old

echo "==> creating pacman.db loopback file..."
CountSize=$(( $(du -s --block-size=$BlockSize $dbroot | cut -f 1) * 5/3 ))

# echo $CountSize
dd if=/dev/zero of=$pacmandb bs=$BlockSize count=$CountSize > /dev/null 2>&1

echo "==> creating $filesystem $Options on $pacmandb ..."
mkfs.$filesystem $Options $pacmandb
       
echo "==> creating temporary mount point $pacman_tmp_mnt_point.."
mkdir $pacman_tmp_mnt_point;
dir $pacman_tmp_mnt_point

echo "==> mounting pacman.db to temporary mount point..."
mount -t $filesystem -o loop $pacmandb $pacman_tmp_mnt_point

echo "==> copying pacman database to temporary mount point..."
cp -a $dbroot. $pacman_tmp_mnt_point

echo "==> unmounting temporary mount point..."
umount $pacman_tmp_mnt_point

echo "==> removing temporary mount point..."
rmdir $pacman_tmp_mnt_point
       
echo "==> moving old /var/lib/pacman to /var/lib/pacman.bak..."
mv $dbroot /var/lib/pacman.bak
       
echo "==> createing new pacman db mount point @ $dbroot..."
mkdir $dbroot

echo "==> Mounting new pacman db..."
mount -t $filesystem -o loop $pacmandb $dbroot

echo "==> md5sum'ing the new database..."
find $dbroot -type f | sort | xargs md5sum >/tmp/pacsums.new

echo "==> checking integrity..."
diff /tmp/pacsums.old /tmp/pacsums.new >/dev/null 2>&1
if [ $? -ne 0 ]; then
        # failed, move the old one back into place
        umount $dbroot
        rm $pacmandb
        mv $dbroot.bak $dbroot
        die_r "integrity check FAILED, reverting to old database"
fi

rm -f /tmp/pacman.lck /tmp/pacsums.old /tmp/pacsums.new

# Replaced by wain: mount is now in /etc/rc.d/pacmandb daemon
#echo "==> Updating /etc/fstab to reflect changes..."
#echo "$pacmandb $dbroot $filesystem loop,defaults 0 0" >> /etc/fstab
 
echo
echo "Finished.  Your pacman database has been caged!.  May the speedy pacman be with you."
echo

exit 0